The invention relates to a method of treating living non-scaly fish, such as catfish, which have been determined to have an earthy, musty taste ("off"-flavor) to restore an acceptable fish flavor. This invention relates more particularly to flavor reinstatement of catfish in commercial catfish ponds found to contain off-flavor catfish.
As of October, 1988, the official total acreage of catfish ponds in Mississippi was 93,700. This acreage has a production potential of in excess of 200 million pounds of catfish. A major problem in the catfish industry is that suitable techniques have not been available for the establishment of acceptable fish flavor in accordance with market requirements.
An effective method of flavor reinstatement has important commercial consequences, since the loss of a considerable investment of effort (towards cultivating catfish to adulthood) resulting from the presence of the unwanted off-flavor in the fish may be avoided. A 1972 survey of several large scale processors reported that over 50% of ponds tested at harvesting time contained fish with such intense off-flavor that harvesting was postponed until flavor improved.
Both off-flavor catfish and insufficient algae management individually result in significant losses in the industry; however, the problems are somewhat interrelated. The presence in the pond of some algal species, especially blue-green algae, imparts an earthy-musty odor and flavor to the fish and aquatic environment. Most off-flavor problems in harvested fish have been attributed to the blue-green species of algae, which are commonly found in dense blooms in fish culture ponds.
A previous approach (U.S. Pat. No. 4,398,937) involving use of the algicide ricinoleic acid to restore acceptable fish flavor, has several drawbacks. Flavor reinstatement is achieved after addition of this fatty acid species to off-flavor fish after a lengthy period of 13 days. Further, addition of a fatty acid compound into the delicately balanced aquatic environment can have negative affects, such as fish weight loss, and toxic effects on non-target species (arthropods, etc.), all of which may result in a disturbed, less productive ecosystem.
Lovell and Sackey approached the flavor problem by introducing off-flavor fish into a flowing, charcoal filtered water, and found that flavor improved after three days and that complete flavor restoration occurred in 10 days. Trans American Fish Soc., (1973) Vol. 102, p. 774-777. This type of treatment has the disadvantages of being both costly and time consuming to employ.